Organization for Autism Research

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Diagnosis

What causes autism?
No one is sure yet. Researchers are working to understand the etiology of autism, but so far nothing has been consistent across all cases. Human physiology is a long chain of intricate events, starting with genetic code and ending in the outward appearances and personalities we see everyday. Along the way, molecules are combined and taken apart, cells are built, proteins synthesized, hormones regulated, neural function promoted, and on down the line. We know that genetics play a significant role; unfortunately no genes have been explicitly implicated. It is also known that exposure to certain environmental toxins such as thalidomide is associated with a later diagnosis of autism. We cannot rule out the possibility that other toxins may again cause similar symptoms.

Diagnosis
With the documented benefits of early intervention for learners with an autism spectrum disorder (ASD), the earlier the diagnosis can be made, the better. As there is no genetic or medical test for ASDs, clinicians rely on behavioral observation, generally quantified through the use of a standardized diagnostic scale, to arrive at the diagnosis. In general, diagnosis is a two step process: 1) screening, and 2) a comprehensive diagnostic evaluation.

Screening
Most “well child” check-ups include a developmental screening. Parent observations, impressions and concerns are an essential part of the screening and may be supported by such “documentary” information as family videos and baby albums. Once concerns are voiced, the parents may be asked to complete any of a number of standardized screening instruments such as the Checklist for Autism in Toddlers (CHAT) or the Screening Tool for Autism in Two-Year-Olds (STAT). If following the screening process there continues to be concern, a comprehensive diagnostic evaluation is indicated.

Comprehensive Diagnostic Evaluation
In order to rule in or rule out an ASD diagnosis a comprehensive diagnostic evaluation is required. This evaluation is generally done by a team of trained professionals that may include a psychologist, a neurologist, a psychiatrist, a speech and language pathologist, or other relevant professional (e.g., occupational therapist). Given the complexity often associated with ASDs, special attention during the evaluation should be paid to neurological testing along with in-depth cognitive and language testing. Other tests may include a hearing evaluation and a lead screening. Lastly, assessments specifically designed to reliably identify presence of an ASD are used. Primary among these is the Autism Diagnostic Observation Schedule (ADOS) but the Autism Diagnostic Interview-Revised (ADI-R) and the Childhood Autism Rating Scale (CARS) are also commonly used.

What next?
Hearing the diagnosis of autism is an overwhelming and potentially devastating blow to families. However, the time of diagnosis is also the time to stay focused and ask questions. In addition to providing the diagnosis, members of the evaluation team are a family’s best, most immediate source for information, recommendations, direction and referrals. It is important that families not leave this meeting without the names and numbers of trained professionals, programs and related resources in their geographic area. Early diagnosis can lead to effective early intervention which can lead to significant gains for the newly diagnosed individual but only if the family now knows where, and to whom, to turn.

From "What Is Autism Spectrum Disorder?" at the National Institutes of Mental Health, available online here.